Zade-Oppen A M, Adragna N C, Tosteson D C
Department of Physiology and Biophysics, Harvard Medical School, Boston, Massachusetts 02115.
J Membr Biol. 1988 Aug;103(3):217-25. doi: 10.1007/BF01993981.
Ouabain-resistant effluxes from pretreated cells containing K+/Na+ = 1.5 into K+ and Na+ free media were measured. Furosemide-sensitive cation effluxes from cells with nearly normal membrane potential and pH were lower in NO3- media than in Cl- media; they were reduced when pH was lowered in Cl- media. When the membrane potential was positive inside furosemide increased the effluxes of Na+ and K+ (7 experiments). With inside-positive membrane potential the furosemide-insensitive effluxes were markedly increased, they decreased with decreasing pH at constant internal Cl- and also when internal Cl- was reduced at constant pH. The correlation between cation flux and the membrane potential was different for cells with high or low internal chloride concentrations. The data with chloride greater than or equal to 47 mM showed a better fit with the single-barrier model than with the infinite number-of-barriers model. With low chloride no significant correlation between flux and membrane potential was found. The data are not compatible with pure independent diffusion of Na+ and K+ in the presence of ouabain and furosemide.
测量了预处理细胞（钾离子/钠离子 = 1.5）在无钾离子和钠离子的培养基中对哇巴因耐药的流出情况。在硝酸根培养基中，膜电位和pH值接近正常的细胞对速尿敏感的阳离子流出量低于氯离子培养基；当氯离子培养基中的pH值降低时，阳离子流出量减少。当膜电位内正外负时，速尿会增加钠离子和钾离子的流出量（7次实验）。在膜电位内正外负时，速尿不敏感的流出量显著增加，在内部氯离子浓度恒定的情况下，随着pH值降低，流出量减少，在pH值恒定的情况下，随着内部氯离子浓度降低，流出量也减少。内部氯离子浓度高或低的细胞，阳离子通量与膜电位之间的相关性不同。氯离子浓度大于或等于47 mM的数据与单屏障模型的拟合度优于无限屏障模型。当氯离子浓度低时，未发现通量与膜电位之间有显著相关性。这些数据与在哇巴因和速尿存在的情况下钠离子和钾离子的纯独立扩散不相符。
